1. Field of the Invention
The present invention relates to a laminated ceramic electronic component and a method for manufacturing the same, and more particularly, to a laminated ceramic electronic component including an external terminal electrode, which is formed by plating so as to be directly electrically connected at least partially to a plurality of internal electrodes, and a method for manufacturing the same.
2. Description of the Related Art
External electrodes for a laminated ceramic capacitor as an example of laminated ceramic electronic components are typically formed by applying a conductive paste to ends of a component main body and subjecting the conductive paste to firing. However, the external electrodes formed by this method are large in thickness, from several tens of μm to several hundreds of μm.
Therefore, in order to limit the dimensions of the laminated ceramic capacitor up to certain specifications, there has been undesirably a need to reduce the effective volume for ensuring an electrostatic capacitance, because there is a need to ensure the volume for the external electrodes.
Japanese Patent Application Laid-Open No. 63-169014 discloses a conductive metal film deposited by electroless plating on the entire sidewall surface of a component main body, at which internal electrodes are exposed, so as to short circuit the internal electrodes exposed at the sidewall surface, and used as an external electrode. According to the technique disclosed in Japanese Patent Application Laid-Open No. 63-169014, the volume of the external electrode can be reduced, and the effective volume for ensuring an electrostatic capacitance can be thus increased.
In the case of applying plating directly to the exposed ends of the internal electrodes as in the method for forming an external electrode disclosed in Japanese Patent Application Laid-Open No. 63-169014, the exposed ends of the internal electrodes will fail to function adequately as nuclei for plating deposition unless the exposed ends are exposed adequately from the component main body. It is to be noted that the adequate exposure of the exposed ends of the internal electrodes includes not only cases where the exposed ends of the internal electrodes are flush with or project from the outer surface of the component main body, but also cases where the exposed ends are even recessed from the outer surface of the component main body with a relatively short recess length.
However, in usual cases, component main bodies that have just been fired often have exposed ends of internal electrodes that are insufficiently exposed from the component main bodies, and thus, the coverage may be decreased for plating films to serve as external electrodes. In addition, while the adhesion between the external electrode and the component main body is ensured mainly in a joining section between the internal electrodes and the plating film, it is not possible to achieve adequate joining between the internal electrodes and the plating film when the exposed ends of the internal electrodes are not exposed sufficiently. Therefore, the adhesion between the external electrode and the component main body is decreased to cause a gap particularly between outer edges of the plating film and the component main body, thereby easily leading to a decrease in moisture resistance.
Therefore, conventionally, as a pretreatment for a plating step, at least a surface of a component main body at which exposed ends of internal electrodes are present is subjected to polishing, thereby sufficiently exposing the exposed ends of the internal electrodes from the component main body. For the polishing, in general, a sandblasting method or a barrel polishing method is applied, for example. However, a relatively long processing time, which is not less than a certain period of time, has been required, in order to ensure the degree of exposing the internal electrodes by applying a sandblasting method or a barrel polishing method.
On the other hand, in spite of performing the polishing step by a sandblasting method or a barrel polishing method, which should be carried out for the purpose of ensuring the degree of exposure of the internal electrodes as described above, the longer processing time of the polishing step may in return decrease the fixing strength of ends of the plating film so as to decrease the moisture resistance.
Laminated ceramic electronic components other then the laminated ceramic capacitors can also encounter the same problems as described above.